各位大神，怎么在java中查询上月同周的第一天和最后一天？

import java.util.Calendar;
import java.util.Date;
public class Test {
public static void main(String args[]) {
System.out.println(getLastDayOfMonth(new Date()));
}
public static Date getLastDayOfMonth(Date sDate1) {
Calendar cDay1 = Calendar.getInstance();
cDay1.setTime(sDate1);
final int lastDay = cDay1.getActualMaximum(Calendar.DAY_OF_MONTH);
Date lastDate = cDay1.getTime();
lastDate.setDate(lastDay);
return lastDate;
}
}